diff options
Diffstat (limited to 'fs/erofs/erofs_fs.h')
| -rw-r--r-- | fs/erofs/erofs_fs.h | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h new file mode 100644 index 000000000000..b1ee5654750d --- /dev/null +++ b/fs/erofs/erofs_fs.h @@ -0,0 +1,316 @@ +/* SPDX-License-Identifier: GPL-2.0-only OR Apache-2.0 */ +/* + * EROFS (Enhanced ROM File System) on-disk format definition + * + * Copyright (C) 2017-2018 HUAWEI, Inc. + * http://www.huawei.com/ + * Created by Gao Xiang <gaoxiang25@huawei.com> + */ +#ifndef __EROFS_FS_H +#define __EROFS_FS_H + +#define EROFS_SUPER_OFFSET 1024 + +/* + * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should + * be incompatible with this kernel version. + */ +#define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001 +#define EROFS_ALL_FEATURE_INCOMPAT EROFS_FEATURE_INCOMPAT_LZ4_0PADDING + +/* 128-byte erofs on-disk super block */ +struct erofs_super_block { + __le32 magic; /* file system magic number */ + __le32 checksum; /* crc32c(super_block) */ + __le32 feature_compat; + __u8 blkszbits; /* support block_size == PAGE_SIZE only */ + __u8 reserved; + + __le16 root_nid; /* nid of root directory */ + __le64 inos; /* total valid ino # (== f_files - f_favail) */ + + __le64 build_time; /* inode v1 time derivation */ + __le32 build_time_nsec; /* inode v1 time derivation in nano scale */ + __le32 blocks; /* used for statfs */ + __le32 meta_blkaddr; /* start block address of metadata area */ + __le32 xattr_blkaddr; /* start block address of shared xattr area */ + __u8 uuid[16]; /* 128-bit uuid for volume */ + __u8 volume_name[16]; /* volume name */ + __le32 feature_incompat; + + __u8 reserved2[44]; +}; + +/* + * erofs inode datalayout (i_format in on-disk inode): + * 0 - inode plain without inline data A: + * inode, [xattrs], ... | ... | no-holed data + * 1 - inode VLE compression B (legacy): + * inode, [xattrs], extents ... | ... + * 2 - inode plain with inline data C: + * inode, [xattrs], last_inline_data, ... | ... | no-holed data + * 3 - inode compression D: + * inode, [xattrs], map_header, extents ... | ... + * 4~7 - reserved + */ +enum { + EROFS_INODE_FLAT_PLAIN = 0, + EROFS_INODE_FLAT_COMPRESSION_LEGACY = 1, + EROFS_INODE_FLAT_INLINE = 2, + EROFS_INODE_FLAT_COMPRESSION = 3, + EROFS_INODE_DATALAYOUT_MAX +}; + +static inline bool erofs_inode_is_data_compressed(unsigned int datamode) +{ + return datamode == EROFS_INODE_FLAT_COMPRESSION || + datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY; +} + +/* bit definitions of inode i_advise */ +#define EROFS_I_VERSION_BITS 1 +#define EROFS_I_DATALAYOUT_BITS 3 + +#define EROFS_I_VERSION_BIT 0 +#define EROFS_I_DATALAYOUT_BIT 1 + +/* 32-byte reduced form of an ondisk inode */ +struct erofs_inode_compact { + __le16 i_format; /* inode format hints */ + +/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ + __le16 i_xattr_icount; + __le16 i_mode; + __le16 i_nlink; + __le32 i_size; + __le32 i_reserved; + union { + /* file total compressed blocks for data mapping 1 */ + __le32 compressed_blocks; + __le32 raw_blkaddr; + + /* for device files, used to indicate old/new device # */ + __le32 rdev; + } i_u; + __le32 i_ino; /* only used for 32-bit stat compatibility */ + __le16 i_uid; + __le16 i_gid; + __le32 i_reserved2; +}; + +/* 32 bytes on-disk inode */ +#define EROFS_INODE_LAYOUT_COMPACT 0 +/* 64 bytes on-disk inode */ +#define EROFS_INODE_LAYOUT_EXTENDED 1 + +/* 64-byte complete form of an ondisk inode */ +struct erofs_inode_extended { + __le16 i_format; /* inode format hints */ + +/* 1 header + n-1 * 4 bytes inline xattr to keep continuity */ + __le16 i_xattr_icount; + __le16 i_mode; + __le16 i_reserved; + __le64 i_size; + union { + /* file total compressed blocks for data mapping 1 */ + __le32 compressed_blocks; + __le32 raw_blkaddr; + + /* for device files, used to indicate old/new device # */ + __le32 rdev; + } i_u; + + /* only used for 32-bit stat compatibility */ + __le32 i_ino; + + __le32 i_uid; + __le32 i_gid; + __le64 i_ctime; + __le32 i_ctime_nsec; + __le32 i_nlink; + __u8 i_reserved2[16]; +}; + +#define EROFS_MAX_SHARED_XATTRS (128) +/* h_shared_count between 129 ... 255 are special # */ +#define EROFS_SHARED_XATTR_EXTENT (255) + +/* + * inline xattrs (n == i_xattr_icount): + * erofs_xattr_ibody_header(1) + (n - 1) * 4 bytes + * 12 bytes / \ + * / \ + * /-----------------------\ + * | erofs_xattr_entries+ | + * +-----------------------+ + * inline xattrs must starts in erofs_xattr_ibody_header, + * for read-only fs, no need to introduce h_refcount + */ +struct erofs_xattr_ibody_header { + __le32 h_reserved; + __u8 h_shared_count; + __u8 h_reserved2[7]; + __le32 h_shared_xattrs[0]; /* shared xattr id array */ +}; + +/* Name indexes */ +#define EROFS_XATTR_INDEX_USER 1 +#define EROFS_XATTR_INDEX_POSIX_ACL_ACCESS 2 +#define EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT 3 +#define EROFS_XATTR_INDEX_TRUSTED 4 +#define EROFS_XATTR_INDEX_LUSTRE 5 +#define EROFS_XATTR_INDEX_SECURITY 6 + +/* xattr entry (for both inline & shared xattrs) */ +struct erofs_xattr_entry { + __u8 e_name_len; /* length of name */ + __u8 e_name_index; /* attribute name index */ + __le16 e_value_size; /* size of attribute value */ + /* followed by e_name and e_value */ + char e_name[0]; /* attribute name */ +}; + +static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount) +{ + if (!i_xattr_icount) + return 0; + + return sizeof(struct erofs_xattr_ibody_header) + + sizeof(__u32) * (le16_to_cpu(i_xattr_icount) - 1); +} + +#define EROFS_XATTR_ALIGN(size) round_up(size, sizeof(struct erofs_xattr_entry)) + +static inline unsigned int erofs_xattr_entry_size(struct erofs_xattr_entry *e) +{ + return EROFS_XATTR_ALIGN(sizeof(struct erofs_xattr_entry) + + e->e_name_len + le16_to_cpu(e->e_value_size)); +} + +/* available compression algorithm types (for h_algorithmtype) */ +enum { + Z_EROFS_COMPRESSION_LZ4 = 0, + Z_EROFS_COMPRESSION_MAX +}; + +/* + * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on) + * e.g. for 4k logical cluster size, 4B if compacted 2B is off; + * (4B) + 2B + (4B) if compacted 2B is on. + */ +#define Z_EROFS_ADVISE_COMPACTED_2B_BIT 0 + +#define Z_EROFS_ADVISE_COMPACTED_2B (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT) + +struct z_erofs_map_header { + __le32 h_reserved1; + __le16 h_advise; + /* + * bit 0-3 : algorithm type of head 1 (logical cluster type 01); + * bit 4-7 : algorithm type of head 2 (logical cluster type 11). + */ + __u8 h_algorithmtype; + /* + * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096; + * bit 3-4 : (physical - logical) cluster bits of head 1: + * For example, if logical clustersize = 4096, 1 for 8192. + * bit 5-7 : (physical - logical) cluster bits of head 2. + */ + __u8 h_clusterbits; +}; + +#define Z_EROFS_VLE_LEGACY_HEADER_PADDING 8 + +/* + * Fixed-sized output compression ondisk Logical Extent cluster type: + * 0 - literal (uncompressed) cluster + * 1 - compressed cluster (for the head logical cluster) + * 2 - compressed cluster (for the other logical clusters) + * + * In detail, + * 0 - literal (uncompressed) cluster, + * di_advise = 0 + * di_clusterofs = the literal data offset of the cluster + * di_blkaddr = the blkaddr of the literal cluster + * + * 1 - compressed cluster (for the head logical cluster) + * di_advise = 1 + * di_clusterofs = the decompressed data offset of the cluster + * di_blkaddr = the blkaddr of the compressed cluster + * + * 2 - compressed cluster (for the other logical clusters) + * di_advise = 2 + * di_clusterofs = + * the decompressed data offset in its own head cluster + * di_u.delta[0] = distance to its corresponding head cluster + * di_u.delta[1] = distance to its corresponding tail cluster + * (di_advise could be 0, 1 or 2) + */ +enum { + Z_EROFS_VLE_CLUSTER_TYPE_PLAIN = 0, + Z_EROFS_VLE_CLUSTER_TYPE_HEAD = 1, + Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD = 2, + Z_EROFS_VLE_CLUSTER_TYPE_RESERVED = 3, + Z_EROFS_VLE_CLUSTER_TYPE_MAX +}; + +#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS 2 +#define Z_EROFS_VLE_DI_CLUSTER_TYPE_BIT 0 + +struct z_erofs_vle_decompressed_index { + __le16 di_advise; + /* where to decompress in the head cluster */ + __le16 di_clusterofs; + + union { + /* for the head cluster */ + __le32 blkaddr; + /* + * for the rest clusters + * eg. for 4k page-sized cluster, maximum 4K*64k = 256M) + * [0] - pointing to the head cluster + * [1] - pointing to the tail cluster + */ + __le16 delta[2]; + } di_u; +}; + +#define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \ + (round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \ + sizeof(struct z_erofs_map_header) + Z_EROFS_VLE_LEGACY_HEADER_PADDING) + +/* dirent sorts in alphabet order, thus we can do binary search */ +struct erofs_dirent { + __le64 nid; /* node number */ + __le16 nameoff; /* start offset of file name */ + __u8 file_type; /* file type */ + __u8 reserved; /* reserved */ +} __packed; + +/* + * EROFS file types should match generic FT_* types and + * it seems no need to add BUILD_BUG_ONs since potential + * unmatchness will break other fses as well... + */ + +#define EROFS_NAME_LEN 255 + +/* check the EROFS on-disk layout strictly at compile time */ +static inline void erofs_check_ondisk_layout_definitions(void) +{ + BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128); + BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32); + BUILD_BUG_ON(sizeof(struct erofs_inode_extended) != 64); + BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12); + BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4); + BUILD_BUG_ON(sizeof(struct z_erofs_map_header) != 8); + BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8); + BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12); + + BUILD_BUG_ON(BIT(Z_EROFS_VLE_DI_CLUSTER_TYPE_BITS) < + Z_EROFS_VLE_CLUSTER_TYPE_MAX - 1); +} + +#endif + |